Ossenkopf, V. and Lis, D. and Bell, T. A. and Blake, G. and Boogert, A. and Emprechtinger, M. and Lord, S. and Morris, P. and Phillips, T. G. and Zmuidzinas, J. (2010) Detection of interstellar oxidaniumyl: Abundant H_2O^+ towards the star-forming regions DR21, Sgr B2, and NGC6334. Astronomy and Astrophysics, 518 . L111. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:20101202-145243225
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Aims. We identify a prominent absorption feature at 1115 GHz, detected in first HIFI spectra towards high-mass star-forming regions, and interpret its astrophysical origin. Methods. The characteristic hyperfine pattern of the H_2O^+ ground-state rotational transition, and the lack of other known low-energy transitions in this frequency range, identifies the feature as H_2O^+ absorption against the dust continuum background and allows us to derive the velocity profile of the absorbing gas. By comparing this velocity profile with velocity profiles of other tracers in the DR21 star-forming region, we constrain the frequency of the transition and the conditions for its formation. Results. In DR21, the velocity distribution of H_2O^+ matches that of the [C_(II)] line at 158 μm and of OH cm-wave absorption, both stemming from the hot and dense clump surfaces facing the H_(II)-region and dynamically affected by the blister outflow. Diffuse foreground gas dominates the absorption towards Sgr B2. The integrated intensity of the absorption line allows us to derive lower limits to the H_2O^+ column density of 7.2 × 10^(12) cm^(−2) in NGC 6334, 2.3 × 10^(13) cm^(−2) in DR21, and 1.1 × 10^(15) cm^(−2) in Sgr B2.
|Additional Information:||© 2010 ESO. Received 30 March 2010, Accepted 7 May 2010, Published online 16 July 2010. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. HIFI has been designed and built by a consortium of institutes and university departments from across Europe, Canada and the United States under the leadership of SRON Netherlands Institute for Space Research, Groningen, The Netherlands and with major contributions from Germany, France and the US. Consortium members are: Canada: CSA, U.Waterloo; France: CESR, LAB, LERMA, IRAM; Germany: KOSMA, MPIfR, MPS; Ireland, NUI Maynooth; Italy: ASI, IFSI-INAF, Osservatorio Astrofisico di Arcetri- INAF; Netherlands: SRON, TUD; Poland: CAMK, CBK; Spain: Observatorio AstronÃ¸smico Nacional (IGN), Centro de AstrobiologÃŋa (CSIC-INTA). Sweden: Chalmers University of Technology - MC2, RSS & GARD; Onsala Space Observatory; Swedish National Space Board, Stockholm University - Stockholm Observatory; Switzerland: ETH Zurich, FHNW; USA: Caltech, JPL, NHSC. This work was supported by the German Deutsche Forschungsgemeinschaft, DFG project number Os 177/1–1. HSPM is grateful to the Bundesministerium für Bildung und Forschung (BMBF) for financial support aimed at maintaining the Cologne Database for Molecular Spectroscopy, CDMS. This support has been administered by the Deutsches Zentrum für Luft- und Raumfahrt (DLR). D.C.L. is supported by the NSF, award AST-0540882 to the Caltech Submillimeter Observatory. A portion of this research was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space administration.|
|Subject Keywords:||astrochemistry, line: identification, molecular data, ISM: abundances, ISM: molecules, ISM: clouds|
|Official Citation:||Detection of interstellar oxidaniumyl: Abundant H2O+ towards the star-forming regions DR21, Sgr B2, and NGC6334 V. Ossenkopf, H. S. P. Müller, D. C. Lis, P. Schilke, T. A. Bell, S. Bruderer, E. Bergin, C. Ceccarelli, C. Comito, J. Stutzki, A. Bacman, A. Baudry, A. O. Benz, M. Benedettini, O. Berne, G. Blake, A. Boogert, S. Bottinelli, F. Boulanger, S. Cabrit, P. Caselli, E. Caux, J. Cernicharo, C. Codella, A. Coutens, N. Crimier, N. R. Crockett, F. Daniel, K. Demyk, P. Dieleman, C. Dominik, M. L. Dubernet, M. Emprechtinger, P. Encrenaz, E. Falgarone, K. France, A. Fuente, M. Gerin, T. F. Giesen, A. M. di Giorgio, J. R. Goicoechea, P. F. Goldsmith, R. Güsten, A. Harris, F. Helmich, E. Herbst, P. Hily-Blant, K. Jacobs, T. Jacq, Ch. Joblin, D. Johnstone, C. Kahane, M. Kama, T. Klein, A. Klotz, C. Kramer, W. Langer, B. Lefloch, C. Leinz, A. Lorenzani, S. D. Lord, S. Maret, P. G. Martin, J. Martin-Pintado, C. McCoey, M. Melchior, G. J. Melnick, K. M. Menten, B. Mookerjea, P. Morris, J. A. Murphy, D. A. Neufeld, B. Nisini, S. Pacheco, L. Pagani, B. Parise, J. C. Pearson, M. Pérault, T. G. Phillips, R. Plume, S.-L. Quin, R. Rizzo, M. Röllig, M. Salez, P. Saraceno, S. Schlemmer, R. Simon, K. Schuster, F. F. S. van der Tak, A. G. G. M. Tielens, D. Teyssier, N. Trappe, C. Vastel, S. Viti, V. Wakelam, A. Walters, S. Wang, N. Whyborn, M. van der Wiel, H. W. Yorke, S. Yu and J. Zmuidzinas A&A 518 L111 (2010) DOI: 10.1051/0004-6361/201014577|
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|Deposited By:||Benjamin Perez|
|Deposited On:||02 Dec 2010 23:31|
|Last Modified:||26 Dec 2012 12:42|
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